NSW child killer too scared to call ambos

In the hours after his girlfriend's seven-year-old son hit the ground "real hard" and began convulsing and foaming at the mouth, accused murderer Kodi Maybir says he was too scared to call an ambulance.

Instead, he put a lighter under the boy's hand and feet and hit him in the stomach in a bid to see if the child was faking it.

The Christian hip-hop producer, who has pleaded guilty to manslaughter but not guilty to murder, repeatedly broke down at the Supreme Court on Tuesday as he recounted the last hours of the boy's life in May 2013.

The morning of May 20 started like many others, he said.

Maybir smoked a "couple of cones" at his Oatley music studio in Sydney's south, where he and his then girlfriend Kayla James and her three children were staying.

Meanwhile, as a form of "discipline" he had told the seven-year-old boy, who cannot be named, to stand on a coffee tin, with knees bent and arms outstretched like in reality TV show Survivor.

Once this was over, Maybir said he was just fooling around when he grabbed the boy - and in a move reminiscent of World Wrestling Entertainment - picked him up and threw him.